Hypodermic syringe



Jan. 22, 1935. H, T, c p 1,988,480

"I HYPODERMIC SYRINGE Filed Oct. 22, 1932 Hugh Titfard Camp/(in i5 liflwrneys Patented Jan. 22, 1935 I Q nYPonninvnosynInGn" nugh Titford Campldn, London, England I Application October 22, 1932', Serial No. "639,014

, l In Great Britain May 13, 1932 l 3 claims. (01. 128-218) 7 relates to hypodermic syringes and-particularly relates to means for the operation of :such syringes. r

-- Hypodermic-syringes at presentin commercial use are entirely hand-operated, the casing or body of thesyringe havinga yoke piece for engagement by the fingers of the operator, while the piston or plunger rod fitted-with apressure plate or member for engagementby the ball of the-hand so that by a closing movement of the hand the requisite pressure may be exerted while at the same time the needle of the syringe is directed to the desired position. Suchhandoperated-syringes have the disadvantage that the syringe'is necessarily held at a substantial distance; from the point of the needle and this, in conjunction with the factthat attimes. considerable pressure isnecessary for the operation of the syringe, renders it very diificult to maintain the needle oi the syringe steadily in thedesired position and at therequired depth and/or to prevent-any cross-strain being put-on the i'needle likely to result in its fracture, these disadvantages being particularly pronounced in giving dental injections. j v The present invention has for its object'to provide simple and effective means whereby these disadvantages referred to; are obviated and whereby the operator is enabled to, hold the syringe close to the needle and to operate the syringe with the utmost precision without having to exert pressure by the hand manipulating the syringe. t A I According to the present invention I provide mechanism adapted to be driven by a dental'en- .gine'or other motor andto impart arelatively slow axial movement to the piston or plungerof a hypodermic syringe. According to theinvention, moreovenl provide a casing or the like adapted for connection to, or forming part of, the body of a syringe and mechanism in or carried by'the said casing and adaptedto be actuated by a dental engine or other motor, the mechanism comprising-- anilaxially movable member adapted to co-operate with the piston or plunger of the syringe. The mechanism is constructed and arranged so that the movement of the syringe piston or plunger .is relatively'slow and therefore readily controllable by the operator during theprocess of'injection, and

so that .the possibility. of a too rapid discharge of the syringe, as for instance when the needlepasses [suddenly fromlhard to softtissue, may beavoided. In one (embodiment, the movement of the syringe pistonior plunger is effected by means of a ccof example with reference to the accompanying diagrammatic drawin i i-which:

airially disposed spindle having ascrew-threaded I H portion of fine pitch engaging .with'a rotatable nut carriedbyatubular casing connected to or forming part of the body of the syringe, the

In this embodiment, particularly H dental injections where high pressure issometimes required, the screwed spindle is non-rotatable and is engaged by the rotatably driven through reduction gearing other motorr suitable for mounted nut t from a spindle adapted to cooperate with the flexible or other drive. Preferably,the rotatable nut carries or forms part of a gearwheelwhich meshes with a small pinion mounted on a shaft disposed parallel with the screwed spindle and adapted to c0operate with the flexible or other drive; Owing to the fine pitch of the screwthreadedportionof the spindle, the axial'move :ment of the syringe piston or plunger is very. slow inrelation tothe speed of the engine or motor, and is readily controllable by the usual rattoperatedl switch controlling the dental engine, .while any-sudden acceleration of. the" forward movement of the piston; or plungensuch as-wou1d cause a too rapid ejection of 'the'contentsof the "syringe, is rendered impossible] Advantag'eously, the spindle referred to is so mounted and arranged that at each end of its travel the screwthreaded part 'disengages completely from the nut, thus preventing any damage. to themechanism by over-runnmg of the dental engine or motor.

5' The device. as before. described 1 may be operated directlyorthrougha flexible drive from which, inltheicase of an electric motor, may be hand. a

Y The invention is hereinafterdescribed-byway .1 Figure 1 is aIpart'longitudinal Sages mt spindle being adapted for connection to theusual flexible or other drive from a dental engine or trating a hypodermic lsyringe provided with .mechanism according to theflinvention;

Figure 2 is an end elevation corresponding to Figure 1;. 7 r 7 a In carryingtheinvention. into ,efiect according to the construction illustratediii the drawing injections where exceptionally high' pressure may be required, acasing 10 is provided forfthe accommodation of a small reduction gear, such ,cas h n ir h? fmntran egawattsany, suitable electric, manual or other :motor' threaded boss 10a adapted for the reception of a tubular connecting piece 11, which latter at its front end is internally screw-threaded for engagement with the body 3 of the syringe and is formed with an internal flange or shoulder 11a by which the glass tube 4 of the syringe is held in position preferably with the interposition of a leather or other suitable washer 2c. The screwthreaded' boss'lfia on the front ofthegear casing 10 is of. such-bore astolpermiti the in'sertion o'f the gear wheel 12 of the reduction gear therethrough into its position in the housing 10. At the rear the casing is formed with a screw-threadedshole 10b or boss for the connection of a annular-member 7 formed in the usual manner-to' enga'gwwith the stationary part of the flexible or other drive and carrying a short spindle -1swmehaat rne front end is fitted with a pinion I iadaptedto' mesh with the gear wheel 12, and at its rear end is fitted with a spiked or other couplingpiece '71 fo'r -ehga'ging with th'e corres qndmg pa'rt ofjthe flexible-or bth'e'fdfivel The pinion -14 is smaller th the hole'* .10b--or boss into "which'theconnectmg member 7= is screwed so that the pinion 25 14tl'iu's mayfbeFin's'erted-into its position infl'the basin" 10 through-such hole 10b orbos s. "The spindle? 3oarryin'gthe pinion l ma'y project for engagement withfa co-axial hole'the front the -hkznisi'ng; E'Ihe gear wheel 12--is tinted on a- ""'screwed nut' 5 'which'preferably isfdimed withan outwardly extending flange 5a at its front end, --suchnut *5 being -rotatably ted in 'thecasing -10 co-axialwith the piston orplunger 3a of {the syringe by the engagement bf fche flang'eisa or the nut 5 with the interior or an? my y; extending cylindrical flanged portion 1b of-the tubular connecting "piece ll and by? the engagement of fa rearwardly projecting portion'bb bf the nut 5" Withf afcorresponding fbore "ifqc'or'recess in the re'arfiwallf of the housing 10. 'Ifl eFbore ll'lc also is provided withaninternally "screwdpa'rt-"at the -1fear-forthe meuntm r-a tubular g u de "for the-re r e1 1-- f--'ascrewed sp 8which,asfbeforedesciibedypreferably is proyidedfat each end of the screw threa'ded part 8c wit non sorew -tlii-ea ded parts 'td'adaptdto -f'r'eef*in the nut- 5 at each end "of the'tra'yelof the pin'die'8. fin: order/to'prevnt' rotationpf the shin e 8; a transverse pin f8 may be 'fixed 110': an -:'xtei isionjig-fat the rear endthereoffisuch transterse 8f 'engag'ingwith' longitudinal slots 15a in the guide tube 15' and preferably having pro"- jecting knobsBh orthe likewhich may servefor e eb a f th nit al en a n 'th ew {pa 8'cof thefspindlei 8 withthe nut' 5 and also, i desired, for-observing the'progresspf the 'in- 'iijecti on n jforder to" ensure thatfthere'arf end 6 the screjwed spindle Bis "maintained in" aligniii ntiwiththe-axisof the nut"5,-the extension-8g at" the Tear end of 'the spindle '8 may be" adapted to slide in the guide tube 15, which latter 'it'will be'uiitler'stood extends parallel with theconnect- 'ihg'member '7ffor attachment to the" flexible or other drive and {preferably *is" more or less 'coexte'nsiye" therewith. At 'itsiro'ntend the screwed spindle 8 isbonnected'to the'piston'or plunger 3a pref erablybythe provision of a pin 8e fixed "to, 'or forming partof,"'the spindle Band passing through a clearancehole 9a in a screw or plug 9' screwed tofthef piston orplunger' 3af and co-"operating h a; shoulder at the end of thespindle 8, "the pin egbeing providewwith' a"nutf 9bor head to gagwthejinner endoff'thescrew'or plug 9. The screwed spin'dIeB "prefer'ably'has' a cdmpara- "tively fine thread, for example about GO threads 'to the inch, so that with the aid of the reduction gear a very slow movement of the piston or plunger 3a, in relation to the speed of the dental engine may be obtained with consequent increase in the pressure that can be obtained and in the ease of control.

It will be understood that the invention is not limited to the particular details of construction 'hereinbefore described.

=WhatI claim is:--

1. In a power drive for a hypodermic syringe, a teasing arranged co-axially with the syringe pis- ..ton l and rigidly connected to the syringe barrel,

""a' nutin'ounted in said casing, an axially movable .spindle operativelygoonnected at one end to said piston, said spindle having a screw-threaded portionrarranged'to engage with said nut and to pass completely through said nut at each end of mtheztravel of said spindle and having non-screwthreadedportions arranged to run in the nut whenthe' latter isdisengaged fromthe screwthreaded portion of said spindle, -mea'ns for -operatively connecting said spindle with a -drive shaft and causing *said spindle to' move --ax-ially of and within said-casing for reciprocating the syringe piston,-"-means comprising said c'asi-ng- -for enclosing saidax-iallymovable spin'dldn all sta'ges of "its-axialmovements with said "piston said casing having a longitudinally-extending slot, and '-meansconnected to' said spindleand-"engaging said slot for holding said-:spin'dle -'against '-rotation. v

' 2; In a power drive for' a hypodermic syringe,

a casingarrangedco-axially with "thesyringe piston-"and rigidly connected-to the"syringe-bar- -re1,'- a nut"m'ounted in saidcasing, an --a-xia'lly movable-spindle operativelyconnectedat -'one 'end to"'said "piston, said spind1e "having a screwthreaded :portion arranged to-engage said -nut and to pass completely through the latter'atea'ch "end of the'travel of-"said spindle and-'havingn'omthreaded-portions arrafigdtd'rdn-hn the nut when the latter isdisengaged from-the threaded portion of' said "spindle; means foroperati-vely connecting said spindle with a 'driveshaft twf- 'fect movementor; said --spindle---axi'ally of *and 'twithim'said-tasingfor reciprocating thesyringe pistonfmeans c'omprising s'aid casing -for='enclosing saidaixiallymovable spindlefin all stagesof "its axial inovemen'ts'with said piston; "said-wasing'havinga-longitudinally extending=slot 'means co'nnected to -said spindleand engaging said slot for holding said spindle against rotation to-cause axial movement *thereofyand-a g-rasp associa'ted fwith said last mentioned meansand-extending exteriorly-bf' said casing for manipulation to=reengagethe threaded portion =offsaid-spiridle with said nut. Y 7 H j 3. Means iorfdriving the pistomofi ahypdder- *inic" syringe "from ei-rotary motor, comprisinga gear "c'asing; ;a-'member having" a screw 'thread ed boreandmounteol-rotatably in thesaidgear'casg, 'a-"gean-wheel-"on the-said rotatable member,

tendfromonefend f ace"there ofparallelwiththe member and extending parallel with the said tubular member, and enclosing the outer end of the axially movable spindle in all stages of its movement, said casing having longitudinally extending slotted portions for engaging with means carried by said spindle for preventing rotation of said spindle, a tubular part rigidly connected to the syringe barrel and extending co-axially with the said rotatable member from the end face of the gear casing opposite to that from which the said tubulanmember and tubular element extend, and means for connecting the syringe piston to the said axially movable spindle.

- H. TITFORD CAMPKIN.

CERTIFICATE OF CORRECTION.

Patent No. 1,988,480. January 22, 1935.

HUGH TITFORD CAMPKIN.

it is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 1, second column, line 51, after drawing" insert the words which is particularly suitable for dental or other; and that the said Letters Patent should be read with this correction therein that the same may conform to the record. of the case in the Patent Office.

Signed and sealed this 5th day oi March, A. D. 1935.

Leslie Frazer (Seal) Acting Commissioner of Patents. 

